i would be more worried about my serving plate than the food! i think its just a hassle of you leave your 'plate'.

as for the food, i wouldnt expect to take any left overs home, but if the host offered i would either just take it, or ask if anyone else wants it.

if it were me, i'd ask whoever bought it if they want the food- let them decide! at DD's first birthday, we had so much food left over (which was all supplied by me, mum and MIL) i offered it to people to take home (more so my single uncle, and my nan, as she doesnt do much cooking)